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Lightstream

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Posts posted by Lightstream

  1. 3 hours ago, djnmd said:

     

     

    Hey Lightstream, how did you go with the Oracles? Thanks to this thread I've been able to ID my pair as Oracles and they require some woofer repair too.

    Ahh ... I sold them, the Merlins too. I needed repairs done to a couple of drivers and I decided that since I didn't want keep them anyway, I will just sell them on to someone who will do what needs to be done with them. 

    I have since bought a pair of almost mint B&W 610i's for $30 and they make an excellent spare bit of kit. Main speakers are still the wonderful 1968 Sansui SP300's and they take a mighty lot of beating by many new designs in important ways of communication, speed with detail, and despite the horn mids and tweeters they are also still smoother than the metal dome tweeters of the B&Ws, which have an edge at times. 

    If you are somewhere near the Sunshine Coast, you could send your Oracles to Vitor at Brisbane Speaker Repair and he will work his magic on them. 

    • Like 1
  2. On 19/02/2021 at 11:51 PM, mach1 said:

    Hi thejt,

    I have a very strong suspicion there is a low impedance mosfet follower output stage on the right hand board (the signal would go through just this when gain = zero), otherwise you are looking at an unbuffered 7K anode follower output impedance, which I don’t think is possible (ie it’s a hybrid linestage). This would drive just about any amp with contemptuous ease.

    Here is the circuit diagram, the only FET is in the power supply as a ripple filter, no other buffering. This pre-amp still runs as quiet as the day I put it together, the Psvane 12AU7-Ts as well; they've had several years of use now, 2 1/4 yrs in this pre-amp and another 3 or so in my TRI TRV-88SE integrated amp. It hasn't been a constant thrashing, as such, but no doubt a good couple of thousand hours + all up. 

     I may consider upgrading a few parts yet, possibly the power supply caps for Nichicon KG Gold Tune versions, or similar (they have been stunning in my restored 1977 Perreaux SP100 pre-amp, dropping the noise floor to so low it's not worth even listening for it at full volume and allowing for a new level of bass depth and impact, as well as a more 3D sound stage and dimensional vocals with a new silence around them).

    In the Elekit TU8500, I have Mundorf polypropylene caps in the Line stage and  good quality polyester caps from from output of the phono stage, so I may move the line stage caps to the phono output and replace them with higher level Mundorfs. Just a thought at this stage. As a pre-amp to the hotrodded Silicon Chip headphone amp - with other mods in-between - the results are superb with the venerable Sennheiser HD540 Reference 600 ohm headphones, which have their own upgrades in Mogami cable and pleather pads. 

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  3. Urgently required: a square 14.5mm black plastic pushbutton for a NAD 3020b amplifier. It's all I need to complete a job/project and if anyone has a spare one out there, it would be greatly appreciated! Happy to cover the small cost of postage etc. It would be really nice to get this one out the door and back to it's owner complete. Many thanks in advance!

     

    PS. I have found that the NAD 1020 Preamp has the same square buttons ...as MAYBE does the 7020 receiver.

     

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  4. 2 hours ago, bob_m_54 said:

     

    If the resistor you're talking about is the the 3rd one up from the bottom, (yellow, purple, orange, gold) it's 47K 5%, not 4K7.

    I've just double checked it against some other resistors nearby, it's definitely a red band, not orange. So 4k7 it was, dead as a Dodo now. Thanks for spotting it though, the photo makes look more orange than it actually it. 

     Awaiting a reply from Naim ...... it could be a while. 

    • Like 1
  5. A few photos of the damaged CD5 board. first pic is the power supply for the analogue stage - I'm assuming, as I have no circuit info other than the fact that this is where the external power supply comes in from the Flatcap 2 - the 4k7 resistor on the LHS that feeds one of the transistors bottom left is open circuit even while looking fine. A couple of the other above it have damaged ends yet measure perfectly. 

     Burned resistors are obvious in the next pics, and the power supply diodes, or what's left of them. With pic four, the overheated 4.7 ohm resistor below the RH side of the chip is obviously done for, there are actually two of them around there.  Flatcap 2 (last pic) is fine ... EMPTY but fine. No doubt a lot of money was paid for a mostly empty box, but then again, this one was given to me, so no hard feelings there! 

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  6. Thank you for all that, stereo coffee, I don't know the full "Ant" situation, as it was done a few years ago in the previous owner's possession. Last night I found at least one more resistor that looked fine on the surface and was completely open circuit. Heaven knows how much more damage might have been done to regulators and op-amps and if there is, the board may just need to be replaced altogether and be much better for it. 

     I will write to Naim and see what they can suggest for me. I will also post a pic or two here. 

     

  7. Very much required is any circuit information for a Naim CD5 player (not the later models, except for maybe the CD5i). Some years ago the player got infested with ants and they created a mess that was cleaned up and then later the unit was switched on, blowing two power supply diodes, damaging the board underneath and burning four resistors throughout the board. The rest of it looks fine, the main PS caps are fine and I'm hoping for the very best that the op-amps are fine too. 

     However, four resistors are burnt enough that I can only just make out the markings, though if I've got the values correct they all read quite low, so must be replaced. The rest of the unit looks good to and the Flatcap 2 is perfect. 

     So, I either need circuit information (there's nothing on line from Naim or anywhere else that I can find) or another board, which may be far more than I can afford.

    I know this player is 20 years old now, but I'd love to have the pair up and running perfectly. Any info would be fantastic. 

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  8. Hi all, might there be anyone out there with a couple (or a set) of NAD square black selector knobs (the little square ones) for a NAD 3020B amplifier. Happy to get them posted up here to the Sunshine Coast. Many thanks if someone can help out. There are a couple on UK eBay for $27(!) for ONE, then they want $127 for shipping, go figure for something that weighs just grams. 

  9. On 19/02/2021 at 11:51 PM, mach1 said:

    Hi thejt,

    I have a very strong suspicion there is a low impedance mosfet follower output stage on the right hand board (the signal would go through just this when gain = zero), otherwise you are looking at an unbuffered 7K anode follower output impedance, which I don’t think is possible (ie it’s a hybrid linestage). This would drive just about any amp with contemptuous ease.

    As far as I'm aware, there is no MOSFET buffering at all, the RH board at the front is all power supply and the phono stage at the rear. I have no problem powering any amp in my stable, loads of output ... but looking over my pics again, I see no FETs anywhere .... unless I am very much mistaken. Main power amp in the system is a modded DIGI 125 amp, with all POOGE-style mods Litz wiring for the PS throughout. Runs beautifully. Great transparency and speed. Alive. I will be sticking with the Psvane 12AU7-T2's when I place the valves,  just so transparent from top to bottom. I may consider a set of matched RCA Black Plates as an option, I hear they are rather good, but have no idea if they have the overall transparency of the Psvanes. 

  10. 9 hours ago, audiofeline said:

    These may give you some info to help your detective work:

     

    https://www.stereo.net.au/forums/topic/5411-introducing-greg-ball-aka-ska/   

    + link to research article " Distorting Power Supplies" published in Wireless World (Dec 1990) he referenced in the above post as being the basis of the

    Eidetic GB1 and 2 pre and power amp

    https://worldradiohistory.com/UK/Wireless-World/90s/Wireless-World-1990-12.pdf  (page 1084+)

     

     

    https://www.diyaudio.com/forums/solid-state/67151-eidetic-amplifierguru.html

     

    https://www.diyaudio.com/forums/solid-state/65286-simple-killer-amp-14.html   (link to one of his articles at the end)

     

    GB1a preamp currently advertised on Gumtree, images has brochures and review  https://www.gumtree.com.au/s-ad/ashmore/guitars-amps/amplifier-eidetic-gb1a/1217455088

     

    ETI advertorial:

    https://worldradiohistory.com/hd2/IDX-AUSTRALIA/IDX/Archive-ETI-AU-IDX/IDX/ETI-1987-12-OCR-Page-0046.pdf

     

    GB1b brochure: https://www.stereo.net.au/forums/topic/307761-eidetic-gb1b-power-amplifier-vertical-mosfet-made-in-brisbane/

     

    Thank you for all of that, some of it I can understand and other sections nada, not that techy left-brained :)

    The Gumtree ad is still up and running, but I cannot afford both amp and pre-amp, even though the amp is version 2 with the upgraded op-amps etc. 

    Still no-one seems to have an actual full circuit diagram, so I will just have to persevere on my own for now. 

    On removing the heatsinks clips, I can see that all the mosfets are gain matched to virtually identical tolerances, they are still marked on the back with their values. Great stuff. The small value bjt's used for bias stability etc are all common transistors, so easy to replace if necessary. 

    One thing's for sure, this is NO ordinary circuit design! 

     

     

     

    • Thanks 1
  11. 3 hours ago, The Rock Puppy said:

    From the depths of my memory, I think he went under the name SKA, and sold DIY kits and stuff. That was a long time ago, though, and he's probably long since moved on. Best I've got, sorry.

    It appears he's gone to ground somewhere, but may yet pop up! I did hear that he wasn't well. 

    Still, someone here must surely have had some dealings with this amp and pre-amp, they were quite famous in their day, there MUST be a proper circuit diagram somewhere, surely. 

  12. Hi everyone, the title says it really, I have picked up an Eidetic GB-1b power amp that is undergoing some much needed work to bring it back to top working order again and trying to find a circuit diagram or find the designer has not been successful so far. The LC of the amp has some 500mV of DC on the output and will hum after some 10-15 minutes of running, RC also has around 350mV of DC but doesn't hum .. well not after 15 minutes anyway. It came with no user manual and had been 'fiddled' with. LED hanging out the front of it, another power switch put in that is too small for the cutout and is just push to make rather than the left-right on/off switch that ran horizontally. A cable from the RC board that was supposed to connect to the ground bar was just flopping uselessly around the output terminals. 

     I have no idea how the 1-2 ohm and 6-8 ohm plug at the back works other than it pulls out, maybe the 1-2 ohm setting is with the plug pulled, best guess I can make at the moment. 

    After all these years and by the looks of it some abuse, I am replacing all the caps with Elna Silmic II's on the channel boards. I don't know about the bank of 16 filter caps yet, they are in unmarked silver cans and I have no idea what value they are until I pull a couple  and check them. 

     This version seems to be an early model with the LF357 op-amps installed, though I know the version 2 model uses the OPA627's instead, if I did that I have no idea without circuit information on any other minor changes around that op-amp may be needed. For the moment I'll stick with the LF357s. 

     ALSO, the outputs for DC and bias adjustments are unidentified for the time being, bias level is a mystery so far. 

    As of the moment, all caps on the LC measure fine for capacitance but I am unable to measure leakage for now. A leakage meter would be handy! I haven't got to the RC yet. 

    Any help here would be much appreciated!

    PS I would really love the Eidetic GB-1a pre-amp to match up! Even one that needs some TLC is ok. I'm in enforced retirement, so big $$ don't apply at this time :) 

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  13. 16 minutes ago, Batty said:

    My speakers are 92dB/w/m 8ohm. Admittedly I use a 25w/ch power amp. M2X. but yes I have driven them with the Pass ACA at 8W/ch and it is gooooood.

    I reckon real efficiency is underrated, there are so many really good low wattage amps out there and fortunately there is a bit of a resurgence of efficient speakers, to have music play with utterly no stress at good volume with only a few well designed watts can be a revelation to the ears. I admit to not having heard a good low wattage Pass Labs amp ...  although I have made a Zen pre-amp that needs more work. 

    • Like 1
  14. ? Actually, the horn speakers are so efficient, yet do so with such ease and communication without strain that the room is filled with music without edge or the pushy mids that are typical of so many horns. I am still stunned every time at how the drivers load the very air in a way that is totally unlike drivers that direct sound at you. The SP300's are keepers even if I had to move into a caravan! The Elekit pre-amp barely gets over 7-8 o'clock on the dial, 9 with the turntable input. 

    Many folks don't understand that most amplifiers are only working on a few watts with reasonably efficient speakers. I recently restored a Japanese 2W Peak amplifier from the mid 60's that easily drove the SP300s and Onkyo Radians at around 90-92dB true efficiency and did it with grace and superb transparency. 

     Thunder with the SP300's is easy :) Though never sloppy! Those 12" bass drivers have 8 big Alnico magnets each and terrific electrical dampening, they actually take a good half and hour to really loosen up and become truly lucid, but when they do, oooh the organic, taut fluidity, very natural. Fast too. The cabinets also play little part in the proceedings, they weigh 36kg each. Even the mid horns have eight Alnico magnets each and the waist of each one is U-bolted to a solid cross brace. I'll just bet your system sounds wonderful!

     

    • Thanks 1
  15. 1 hour ago, wen said:

    @Lightstream, i have the Elekit TU-8200R tube amp, built by Chamila of RF Waves in WA, my first tube amp and couldn't be happier, i do not have the skills to complete this sort of project. There are  few WA SNA members who have extolled the tech virtues of Chamila, so i have no doubt of the build quality of my amp. Sold my keeper amp, Exposure 2010, after a couple of weeks of listening to the Elekit, outstanding value for sound/money. Chamila put the labels for the controls under the controls. There have been very few days that it doesnt get listened to. My second system with a Quasimodo gets minimal use at present as well, you will not be disappointed with the 8200

    I would love to build my own TU-8200 some time this year. I am listening to the TU-8500 right at this minute, running into my homebuilt version of the old DIGI 125 amp and extremely efficient 1968 Sansui SP300 speakers (around 104dB, quoted), sounds magnificent! If your TU-8200 runs anything like as efficiently, quiet and reliably as the pre-amp, then you have years of joy ahead of you. I do run Psvane's top of the line 12AU7-T valves and they too have run magnificently for years, though I am considering a new set some time soon, considering they also saw fine service for a few years in a TRI TRV-88SE integrated amp. My absolute favourite valves in this pre-amp, utterly transparent from top to bottom, neutral and silent. 

     I can recommend the various resistor and cap upgrades if you so desire at a later stage. It's terrific that you are getting so much joy from your amp, do you use head[phones with it too? One reviewer was ecstatic running h/phones from that amp. 

  16. Hi everyone, I've picked up a pair of Tannoy Venus II speakers recently with both bass/mid drivers replaced at some stage earlier in their life. One of the 8" drivers is completely free and sounds great, the other buzzes, yet the driver coil does not touch the insides of the magnet, while seeming stiff and restricted, almost as if it can't move freely enough backwards into the magnet. When pulled from the cabinet and laid on it's face, there is plenty of free movement. The other driver is perfect. 

    However, the replacement bass mid cones, while being genuine Tannoy 8 ohm units look quite different from the originals, having much larger dust caps and the corners of the basket do not reach into the cutout of the originals. They also state on the sticker that they are 40W drivers, yet the power handling of the overall speakers are rated at 10-100W. 

    Regardless, they still sound amazingly good ... except for the buzz from one driver. 

     Question now is, do I get the buzzing driver looked at, or find a genuine pair of Venus or Jupiter bass/mid drivers (200mm or 8")? I really do like these speakers, replaying Eva Cassidy's remarkable voice with clarity, focus and without a bright edge, yet projected into space beautifully. Cabinets are very nicely built too, solid and lovely walnut veneer, so I want to keep them, they are the perfect size for my set-up. 

     Does anyone have a set of these original drivers on a shelf, or have some extra information that could help me out here, please? Many thanks! PS My pic is on the top (single speaker), bottom image is from the Net of original units. Quite a difference really. I'd love a set of original drivers if possible. 

     

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  17. Now that I know there are Richter fans here and those who have worked with these speakers, I now have TWO sets of early Richter speakers that require new drivers or driver repairs. 

    Firstly, is a pair of early Merlins that has a damaged 116mm bass driver - not seized - in one cabinet. The whole cone will need replacing, both driver sets measure 6.2 ohms. 

    Cabinets are 320mm x 190mm x 210mm and beautifully dead to the rap on the sides. Very impressive! 

     Secondly, I have picked up a pair of early Oracles that will need both bass/mid drivers replacing, or at least the cones and coils. One is seized solid and the other has a badly damaged cone. It never fails to amaze me the lack of respect some people have for hifi gear. One driver I could put down to a nasty accident, the other, seized solid? Hmm. 

     Anyway, there are quite a lot of folks with these speakers out there and I'd really love to get both of these speaker pairs running to perfection again. 

     Does anyone have spare drivers for these units, OR any advice from those Richter folks in the know? 

    I did send Richter photos of the Merlins (the ID has worn off the serial number patches on both sets) and they said they could do nothing for me because they didn't recognise them. Funny, many other folks on-line knew exactly what they were, as they own or have owned them personally. I will have to have another go with Richter. 

     The Oracles also turn out to be earlier models: sized 484mm x 212 x 298mm with 140mm bass/mid cones to the outside of the foam.  The cabinets are I think Jarrah, really rather nice, solid too. 

     It would be really great if someone can help me out here. I live in Palmwoods on the Sunshine Coast and will likely need to ship drivers to Sydney if there is no good repair shop closer to home. 

     Pictures show the little Merlins first. Thanks everyone. 

     

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  18. Certainly, just go straight to LPgear and you will find the upgrade stylus for this fine cartridge.

    https://www.lpgear.com/product/PICKSXV151200E.html

    There is also a cheaper standard stylus available. The upgraded version is around $80US, which is likely a bargain for a fine vivid line contact stylus. The stock replacement - and I find LPgear's standard replacements are very good, often better than the original  - at less than half that price. Shipping is near the $20-$26 mark. Shipping I find is very good too. Excellent service. 

    There is little information re the stock stylus though, in this case. I'd go the upgrade line contact, but that's just me :) 

    • Like 1
  19. I picked up a lovely little pair of the Celestial Hadleigh speakers recently and both tweeters need replacing. I suppose I can get them re-coiled, therefore keeping the original cones, OR maybe someone out there has a spare set of tweeters from a similar set of Hadleighs that they can part with. 

     I am going to restore the cabinets to remove some scratches and it would be great to get these speakers back in great shape again. Maybe there is an alternative tweeter, but too small a cone diameter would be unlikely to match the larger bass/mid drivers. 

    I've included a couple of pics here.  Thank you to anyone who can help out here!  BTW, the total diameter of the actual cone to the edge of the roll surround is 7cm. 

     

    I did post this in the speaker section and although I've had one comment (thank you), no one has come up with any solution yet. So, if anyone can help with parts, that would be terrific. Maybe I do need to get the coils rewound. Is there anyone who would do a great job in SE Queensland? 

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  20. I picked up a lovely little pair of the Celestial Hadleigh speakers recently and both tweeters need replacing. I suppose I can get them re-coiled, therefore keeping the original cones, OR maybe someone out there has a spare set of tweeters from a similar set of Hadleighs that they can part with. 

     I am going to restore the cabinets to remove some scratches and it would be great to get these speakers back in great shape again. Maybe there is an alternative tweeter, but too small a cone diameter would be unlikely to match the larger bass/mid drivers. 

    I've included a couple of pics here.  Thank you to anyone who can help out here!  BTW, the total diameter of the actual cone to the edge of the roll surround is 7cm. 

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